The Global Grid The science and study of map making is known as cartography. Scientists use two special measurements to describe location: ○ Latitude: the distance north or south of the equator, measured in degrees. ○ Longitude: the distance east or west of the prime meridian, measured in degrees.
The Global Grid Lines of latitude run E-W and measure N-S. The line of latitude around the middle of the globe, at 0 degrees (°), is the equator. Lines of longitude run N-S and measure E-W. The prime meridian marks 0° of longitude.
Map Projections A flat representation of Earth’s surface is called a map. However, we know the Earth is round … Christopher Columbus? Maps can also be called projections since they attempt to show a three-dimensional image in two dimensions. No map is perfect because something will always be distorted (too small, too big, out of place, etc).
Map Projections Cylindrical Projection: A map where the Earth’s surface is projected onto a cylinder wrapped around a globe. The equator is the viewpoint (center of the cylinder). Common example:
Map Projections Azimuthal Projection: A map where the Earth’s surface is projected onto a flat plane at a central point. The poles are the viewpoint (center of the plane). Common example:
Map Projections Conic Projection: A map where the Earth’s surface is projected onto a cone surrounding a globe. The poles are the viewpoint (center of the cone). Common example:
Topographic Maps A topographic map is a representation of Earth’s three-dimensional surface in two dimensions showing elevation. Uses contour lines, or lines showing points of equal elevation. Every position along a single contour line is the same elevation.
Topographic Maps Adjacent contour lines represent a change in elevation. The contour interval is the difference in elevation between adjacent contour lines. Every 5th line is called an index contour, which is a bold and labeled with elevation.
Topographic Maps Contour lines close together represent a steeper slope while lines further apart indicate a gentler slope.
Topographic Maps Contour lines forming a circle represent a hill or mountain.
Topographic Maps A depression is represented by circular contour lines having hachure marks, pointing to the center of the circle.
Topographic Maps Contour lines do not cross each other, divide, or split. Contour lines trend UP valleys and form a “V” or a “U” when they cross a stream.
Topographic Maps A map is drawn to scale where a certain distance on the map is equal to a certain distance at the surface.The scale to the right reads1:24,000. This means 1 uniton the map is equal to 24,000units on the ground.If the 1 stands for 1 cm. onthe map, it stands for 24,000cm. on the ground. How many kilometers does the 24,000 stand for on the ground?
Topographic MapsDIMENSIONAL ANALYSIS AGAIN! ? km. = 24,000 cm. x 1 km. 100,000 cm. Try another: The same scale reads 1:24,000. However, this time, I know the 1 stands for 1 inch. How many feet does the 24,000 stand for on actual ground? ? ft. = 24,000 in. x 1 ft. 12 in.
Map Scale Large Scale – show a small area (ZOOM IN). Example 1:24,000
Map Scale Small Scale – show a large area (ZOOM OUT). Example 1:1,000,000